JEP-01xx: Common Alerting Protocol (CAP) over XMPP

WARNING: This Standards-Track JEP is Experimental. Publication as a Jabber Enhancement Proposal DOES NOT imply acceptance or approval of this proposal. Implementation of the protocol described herein is NOT RECOMMENDED except in an exploratory fashion (e.g., in a proof of concept). Production systems SHOULD NOT deploy implementations of this protocol until it advances to a status of Draft.

Author Information

Peter Saint-Andre

Email: stpeter@jabber.org
JID: stpeter@jabber.org

Boyd Fletcher

Email: Boyd.Fletcher@je.jfcom.mil
JID: bfletcher@jabber.com

JEP Information

Legal Notice

This Jabber Enhancement Proposal is copyright 1999 - 2004 by the Jabber Software Foundation (JSF) and is in full conformance with the JSF's Intellectual Property Rights Policy <http://jabber.org/jsf/ipr-policy.php>. This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, v1.0 or later (the latest version is presently available at <http://www.opencontent.org/openpub/>).

The Common Alerting Protocol [1] (CAP) is an open format for alerts and notifications, defined by OASIS [2]. CAP was developed to address the call, published in a (U.S.) National Science and Technology Council report, for "a standard method ... to collect and relay instantaneously and automatically all types of hazard warnings and reports". Given that the Extensible Messaging and Presence Protocol (XMPP) provides a near-real-time transport mechanism for structured information, and that CAP is defined as an XML data format, it makes sense to define a way to transport CAP information over XMPP. Such a method is defined herein.

Because the alerts and notifications structured via CAP require a "push" medium, they SHOULD be sent via the XML <message/> stanza defined in XMPP Core [4]. The message could be (1) sent directly from the sender to a recipient or list of recipients (which might include a Multi-User Chat [5] room) via standard XMPP messaging or (2) published to a list of subscribers via Publish-Subscribe [6]. Both methods are described below.

In the case of direct messages, the message stanza SHOULD have no 'type' attribute, but MAY have any defined type that is appropriate to the communications context (e.g., "groupchat" in a text conference). The <alert/> element SHOULD be the only child element of the message stanza, but other elements MAY be included as necessary (e.g., a <body/> child in the 'jabber:client' namespace providing a natural-language description of the alert). The 'id' attribute of the <message/> stanza MAY be set to the value of the CAP <identifier/> element.

The following example shows Example A.2 from the CAP specification sent as a direct message.

7. The Internet Assigned Numbers Authority (IANA) is the central coordinator for the assignment of unique parameter values for Internet protocols. For further information, see <http://www.iana.org/>.

8. The Jabber Registrar maintains a list of reserved Jabber namespaces as well as a registry of parameters used in the context of JEPs approved by the JSF. For further information, see <http://www.jabber.org/registrar/>.